The present invention is directed to an intelligent component feeder system for use in robotic assembly devices such as pick and place machines (also known as placement machines or placement equipment). More particularly, the present invention is directed to a system for tracking the contents of a particular component feeder and enabling a host computer to recognize the feeder and its contents when the component feeder is coupled to a network to which the host computer is connected.
Robotic assembly machines are well known in the art. Such devices, which include pick and place machines, are used, for example, in the assembly of electronic printed circuit boards (PCBs). In a conventional pick and place machine, one or more pick-up heads which are movable in X, Y, Z and rotation directions are directed to pick up electronic and similar components from pick-up stations normally supplied with components from a reel held in a component feeder containing a relatively large supply of a particular component. The force used to pick up the components is typically supplied by a vacuum air supply, a mechanical gripper or the like. Once the component is picked up, it is oriented, normally by optical means, and transported to a placement location on a substrate such as a PCB where it is placed. After all components are placed on the PCB, the PCB is normally run through a reflow oven where solder contacts are reflowed to form permanent electrical connections between pads of the PCB and various types of contact pins belonging to the electronic components.
Pick and place machines typically have a number of feeder stations which receive component feeders. Component feeders come in a number of well known standard widths to accommodate standard component reels. In conventional pick and place machines, a program running on a host computer which controls the machine and its operation (the controller) is manually told which feeder station has which components loaded. If an incorrect feeder is put in place and the host computer is not informed, there is generally no way for the pick and place machine to avoid placing incorrect components on the circuit board resulting in a zero manufacturing yield.
Conventional mechanical component feeders operate entirely mechanically. An actuator such as a rod, pin or lever driven by the machinery of the pick and place machine moves under the control of the controller of the pick and place machine. The actuator pushes against a lever of the mechanical component feeder and causes a mechanical response which results in advancing the next component onto the feeder pickup position.
Recently, a number of companies have introduced electronic component feeders. Such devices have their own electrical drive components, motors, microprocessors and other complex circuitry and componentry. These devices provide additional functionality over conventional mechanical component feeders but they have several drawbacks. First, because they are more complex, they are necessarily less reliable. Second, the added complexity comes at a significant cost premium to existing mechanical component feeders. Third, a customer desiring to convert to such electronic component feeders must purchase entirely new pick and place machines, control equipment, feeders and other items. Such conversions may in many cases be prohibitively expensive and do not make use of existing, relatively expensive and still operable equipment, resulting in waste.
When constructing complex PCBs for use in certain types of applications, e.g., airplanes, spacecraft, automobiles, and the like, it is becoming important to be able to determine long after the assembly of the PCB whether an electrical component of a specific type from a specified lot number is part of the assembled PCB. This is referred to as xe2x80x9ctraceabilityxe2x80x9d. For example, when components from a particular lot are determined to have a particularly high failure rate or to contain potentially dangerous errors or defects, it would be desirable to determine which critical PCBs include the potentially defective components so that they can be readily identified, located and checked or replaced prior to failure without the need for checking or replacing all similar boards. Conventional robotic assembly equipment provides no convenient way for providing traceability, i.e., linking component lot numbers with specific assembled PCBs.
Accordingly, it would be desirable to provide an intelligent component feeder system which is retrofitable into existing equipment, makes use of reliable and proven mechanical feeder technology, provides traceability, and is relatively easy and inexpensive to implement.
An intelligent component feeder system includes an intelligent component feeder, an adapter interface for receiving the component feeder and forming needed electrical contacts therewith, and computer software running on a computer system controlling robotic placement equipment. The intelligent component feeder is adapted from a conventional mechanical component feeder and additionally includes a nonvolatile serial memory device which can be accessed using two electrical conductors, a data line and a data ground line. One of the electrical conductors (the data line) is connected to the adapter interface via a spring-type contact so that when the component feeder is placed for use with the robotic placement equipment, an electrical contact is made to the serial memory device through the spring-type contact of the interface adapter. The second of the electrical conductors (the data ground line) is tied to the metal body of the component feeder. Electrical contact is made when the component feeder is clamped into place on the robotic placement equipment. The component feeder holds a reel of components. A bar code label is placed on the reel identifying information about the components stored thereon, such as ID, Lot Number, Quantity, feeder serial number, feeder type, number of feeder actuation, and the like. Each time that the component feeder is placed on the machine, the bar code label on its reel must be read in order to confirm a match between the reel and the data stored in the memory device. When a component reel is removed from the feeder, a new bar code label is generated reflecting any change in the quantity of components stored on the reel. The new bar code label is placed over or replaces the existing bar code label. The software is aware of each component feeder through the adapter interface and knows its feeder position, the ID of the components loaded thereon, the Lot Number of those components, approximate remaining quantity, feeder serial number, and the like.